Subscriber Identity Model, abbreviated as SIM card, in existing mobile communication technologies are widely used in mobile communication terminals. Following development in technologies, various methods are employed in conventional mobile terminals, first to add various intelligent circuit modules into the SIM card of common mobile communication terminals, making the SIM cards not only having basic SIM card functions, but also added other functions that are more pertinent to daily life. RF SIM card is one of these. Chinese patent application No. 200710124354.7 disclosed technologies related to an RF SIM card. RF SIM cards adopt active RF technologies, allowing common SIM cards, with minor modifications, to have the functionalities of mobile payment such as electronic wallets, or access control and other consumer applications.
The RF SIM cards in some applications, for example when using the RF SIM cards as public transit fare IC cards and other RF smart cards, to avoid the phenomena of false reading and erroneous reading of the card, the communication range between the RF SIM card and the RF card reader must be controlled to within a very small range. Thus, the above described communication range control becomes the most important realization difficulty for RF SIM card wireless communication system. Existing technologies utilize the decay of the RF SIM card signal strength to control the wireless communication range between the RF SIM card and the RF card reader. However, RF SIM cards typically are assembled inside mobile communication terminals, and are affected by the shielding effect of the mobile communication terminals. For the same wireless transceiving power of the RF SIM cards being deployed, the RF signals would have different transceiving powers through different types of mobile communication terminals. Thus, it is necessary to build different RF SIM cards with different wireless transceiving powers for different types of mobile communication terminals to control their respective wireless communication ranges to within an appropriate range. This subsequently requires that, before using the RF SIM cards, the users must calibrate the wireless transceiving power of the RF SIM cards according to the types of the mobile communication terminals. In addition, if a user replaces the mobile communication terminal, after each replacement it is necessary to calibrate the RF SIM card again with respect to the wireless transceiving power. This tedious calibration process not only makes the user feel inconvenient, but also does not facilitate the wide applications of the RF SIM cards.